Supported vanadium dihalide-ether complex catalyst

ABSTRACT

A vanadium dichloride-ether complex is carried on a porous support. This complex can be produced by either forming VCl 2  and thereafter complexing the material with an ether or forming an ether complex with VCl 4  or VCl 3  and thereafter reducing the vanadium compound to VCl 2 . It is also possible to carry out the complexing reaction and the reduction essentially simultaneously. The resulting catalyst in combination with a cocatalyst is capable of giving high activity in olefin polymerization and demonstrates good sensitivity to molecular weight control agents, thus allowing the production of a broad spectrum of polymers so far as molecular weight is concerned.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of application Ser. No.06/744,713, filed Jun. 14, 1985, now abandoned, which is a Divisional ofcopending application Ser. No. 682,726, filed Dec. 17, 1984 now U.S.Pat. No. 4,559,318 which in turn was a Continuation-In-Part of copendingapplication Ser. No. 488,887, filed Apr. 26, 1983, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to supported vanadium catalysts for olefinpolymerization.

Vanadium compounds display catalytic activity in a number of diversechemical reactions. Since vanadium is closely related to both chromiumand titanium in the Periodic Table, it is only natural that it has beentried in place of chromium or titanium as a catalyst for thepolymerization of mono-1-olefins, such as ethylene. Peters et al U.S.Pat. No. 3,371,079 discloses silica supported vanadium pentoxide with acocatalyst for polymerizing ethylene. Kearby U.S. Pat. No. 3,271,299discloses aluminum phosphate-supported vanadium pentoxide as ahydrogenation catalyst and suggests aluminum phosphate as a support forchromium or molybdenum for polymerizing ethylene and propylene. However,vanadium catalysts have not been as commercially successful as titaniumor chromium catalysts for olefin polymerization. Supported vanadiumcatalysts have been particularly disappointing. The closest vanadium hascome to being commercially viable as an olefin polymerization catalysthas been in systems more analogous to unsupported titanium systems,i.e., VOCl₃, VCl₄ or VCl₃ used with a reducing agent such as an aluminumhydride. However, the natural tendency of vanadium to catalyze reactionsother than polymerization has been a constant problem limiting itsusefulness in olefin polymerization. Yamaguchi et al U.S. Pat. No.4,202,958 and Natta et al U.S. Pat. No. 3,260,708 disclose unsupportedvanadium halide-ether complexes as catalysts, but such unsupportedsystems tend to cause reactor plugging.

It would be desirable for some applications to produce polymer havingdifferent characteristics from that produced with the chromium systems,such as :or instance, polymer with a different particle shape. Also, itwould be desirable to be able to obtain in non titanium systems themolecular weight sensitivity to hydrogen displayed by titanium catalystsystems.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a vanadium catalyst capableof operating without reactor fouling;

It is a further object of this invention to provide a vanadium catalystcapable of giving high activity;

It is yet a further object of this invention to provide a catalystsystem capable of giving ultra high molecular weight polymer;

It is a further object of this invention to produce the novel compoundsVCl₂.ZnCl₂.2THF and VCl₂.ZnCl₂.4THF;

It is a further object of this invention to provide a novel, highlyactive vanadium catalyst; and

It is a further object of this invention to provide a catalyst havingoutstanding sensitivity to molecular weight control agents such ashydrogen at high activity rates.

In accordance with one aspect of this invention, a vanadiumdihalide-ether complex is carried on a porous support. In accordancewith another aspect of this invention VCl₂.ZnCl₂ 4THF is prepared anddissolved in a chlorinated hydrocarbon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

There are two routes to obtaining the supported vanadium dihalide-ethercomplex of this invention. These are:

(1) Form VX₂ and thereafter complex this material with an ether.

(2) Form an ether complex with VX₄ or VX₃ and thereafter reduce thevanadium compound to VX₂.

There are certain advantages to each of the two methods set outhereinabove but in each instance, the resulting catalyst is a trulyremarkable material capable of overcoming the disadvantages historicallyassociated with vanadium catalysts. The following describes in greaterdetail the two methods set out hereinabove for achieving the catalyst ofthis invention. Since the preferred halide is chloride, the followingdescription assumes X to be chlorine, but fluorides, bromides, andiodides, particularly bromides can also be used in each instance wherechloride is indicated.

The first route is-briefly described as involving the formation of VCl₂and thereafter complexing with an ether. Since VCl₂ is difficult toform, requiring reactions at 500° C. or above and since VCl₂ does notappear to react directly with common ethers to form a complex, theadduct must be prepared from an intermediate such as a VCl₂ -alcoholcomplex which can be obtained by electrolytic reduction of VCl₃ inalcohol. For instance, VCl₂.2CH₃ OH can be produced by electrolyticreduction of VCl₃ in methanol as is known in the art. This is shown inJ. H. Seifert, and T. Auel, Journal of Inorganic and Nuclear Chemistry,30, 2081-2086 (1968), the disclosure of which is hereby incorporated byreference. The resulting VCl₂ -alcohol complex can then be reacted withan ether to form the ether complex. For instance, with THF the resultingvanadium dihalide-ether complex is VCl₂.2THF. Herein THF is used as theabbreviation for tetrahydrofuran. J. H. Seifert and T. Auel alsodisclose preparation of VBr₂.2CH₃ OH in Z. Anorg. Allg. Chem., 360,50-61 (1968), the disclosure of which is hereby incorporated byreference. By these means, VX₂.ether is produced as described below.

Suitable ethers are 1,3-dioxane and those ethers of the general formulaR--(OCH₂ CH₂)_(n) OR' where R and R' are the same or different andrepresent hydrocarbon groups with 1 to 12 carbon atoms and n is 0 or 1.The R and R' groups may be bonded together to form a ring. Exemplarycompounds include aliphatic ethers such as diethyl ether, diisopropylether, di-n-propyl ether, isopropyl ethyl ether, di-n-butyl ether, ethyln-butyl ether, di-n-amyl ether, di-n-octyl ether, di-n-decyl ether anddi-n-dodecyl ether. Suitable cyclic ethers include tetrahydrofuran (THF)and tetrahydropyran with THF being preferred. The ether and the alcoholadduct can be reacted by contacting the methanol complex with excessether at ambient temperature to slightly above, although temperatures of0° C. to about 50° C. can be used.

The second and presently preferred route for producing the vanadiumdichloride-ether complex is to form a vanadium tetrachloride-or vanadiumtrichloride-ether complex and thereafter to reduce the vanadium of thecomplex to VCl₂. In this embodiment, the ether is selected from theethers described hereinabove except that it must be cyclic. Again, thepreferred ether is tetrahydrofuran. The reason :or this is that whenstraight chain ethers are reacted with VCl₄ which is then reduced, acomplex is formed with vanadium in the +3 state which is difficult tofurther reduce.

The starting material for forming the complex can be either VCl₄ orVCl₃, both of which are commercially available materials.

The formation of the complex can be achieved simply by contacting theether with the vanadium tetrachloride or vanadium trichloride at roomtemperature. If desired an elevated or reduced temperature can be used,i.e., from -100° to 200° C. but this is not necessary in view of thesuitability of room temperature. Alternatively, a solvent can beutilized Suitable solvents include hexane, heptane, cyclohexane,benzene, toluene, dichloromethane, chloroform and carbon tetrachloride.An inert solvent including a mixture of halogenated and aromaticcomponents may offer a slight advantage over other solvents. A catalyticagent may be utilized to speed up the reaction forming the complex.Suitable catalysts include elemental zinc, elemental magnesium, sodiumborohydride and sodium hydride, preferably sodium hydride. With VCl₄lower temperatures are preferred than with VCl₃. Most preferred withVCl₄ is a temperature of 0° to 20° C. with no solvent. If a solvent isused with VCl₄ higher temperatures can be used (because the solvent willcarry away some of the heat from the exothermic reaction) but are notnecessary. With VCl₃ it is also preferred not to use a solvent butsightly higher temperatures are preferred. Operating in ether with nosolvent at reflux temperatures (65° C. for THF) is particularly suitablewith VCl₃ although on a commercial scale it is likely that slightlyhigher temperatures and a slight pressure would be used sufficient tokeep the ether in the liquid state.

After formation of the vanadium tetrachloride or vanadium trichloridecomplex with the cyclic ether, the vanadium of the resulting complex isreduced so as to give vanadium dichloride. Some of the reduction can becarried out using any conventional reducing agent such as organoaluminumand organoboron compounds. Examples of such compounds are those of theformula R₃ Al, R₂ AlX, RAlX₂ and R₃ B where R is a 1 to 12, preferably 2to 4 carbon atom hydrocarbyl radical, most preferably ethyl, propyl orbutyl and X is chlorine, fluorine or bromine preferably chlorine.However, at least the last part of the reduction is carried out usingzinc metal or alkyl zinc compounds of the formula R₂ Zn where R is asdescribed above. The preferred material is elemental zinc in a finepowdered form. The zinc or zinc compounds are capable of reducingvanadium to the +2 valence and give a vanadium zinc ether complexproduct that is easily dispersed on the support and which is enhanced bythe presence of the support. With VCl₄ there seems to be an advantage tostepwise reduction from V⁺⁴ to V⁺³ to V⁺².

It is preferred, however, to start with vanadium trichloride rather thanvanadium tetrachloride simply because less zinc is required and thusless zinc is left in the final catalyst. The presence of the zinc has adetrimental effect on the activity and hence the preference for thevanadium trichloride as the starting material.

These principles can be summarized as follows:

Preparation of 2VCl₂. ZnCl₂.6THF is best done from VCl₃.3THF with 1/2gram atom Zn metal or 1/2 mole Et₂ Zn (diethylzinc) per gram atom V,preferably at about 90° C.

The VCl₃.3THF may be prepared from VCl₃ +THF and NaH (catalytic amount)or from VCl₄ in THF and 1/3 Et₃ B (triethylborane). The Et₃ B reductionproceeds more rapidly with heating to ≅80° C.

Thus, vanadium trichloride when extracted with tetrahydrofuran in thepresence of sodium hydride yields VCl₃.3THF. This red-orange compoundmay be further reduced to a green compound of the formula2VCl₂.ZnCl₂.6THF. This is accomplished with the reducing agentsdisclosed hereinabove. Broadly, reaction conditions when starting withVCl₃ are as follows: Anhydrous VCl₃ and a catalytic amount of catalystsuch as sodium hydride (<0.1 mol %) are refluxed several hours in THFuntil a burgundy red solution is obtained. Without isolating VCl₃.3THF,one half equivalent of Zn dust is added and refluxing continued for anadditional hour. After cooling to room temperature, 2VCl₂.ZnCl₂.6THF isobserved as a green, microcrystalline mass in the bottom of the reactorvessel. The reaction solvent is decanted and the product washed once,with cold THF and once with pentane, then dried under vacuum at roomtemperature. As with the formation of the complex, the reduction in acommercial scale operation will advantageously be carried out at atemperature slightly above reflux and under slight pressure.

Thus temperatures of 20° to 130° C. and pressures ranging fromatmospheric to 100 psig can be used so as to maintain the ether inliquid condition. Generally, conditions are chosen so that only moderatepressure is required. Times are generally from 15 minutes to two hoursor more. With VCl₄ the ether brings about a reduction to VCl₃ at highertemperatures. This offers both advantages and disadvantages. Operatingat lower temperatures is more simple because the amount of reducingagent can be determined precisely. If some unknown amount of reductionoccurs at the high temperature, this makes it more difficult tocalculate the reducing agent (such as zinc metal or organozinccompounds) needed to go to V⁺² but under these circumstances less zincis in the final catalyst which is good.

When VCl₄ is used as a starting material, the situation is thus somewhatmore involved than with VCl₃. A complex between VCl₄ and the ether, suchas THF of the formula VCl₄.2THF, may be prepared by reaction in asolvent such as hexane, heptane, cyclohexane, benzene, toluene,dichloromethane, chloroform, and carbon tetrachloride. Aromatic andhalogenated solvents may be preferred. Alternatively, the ether may bethe only solvent thus eliminating the step of solvent removal. In thereduction of VCl₄.2THF with zinc metal or a zinc compound such asdiethylzinc, the Zn/V atom ratio determines the product mix. Thus, forZn/V atom ratio=0.5, the major product is VCl₃.ZnCl₂.5THF with someVCl₃.3THF. For Zn/V atom ratio=1.0, the major product is VCl₂.ZnCl₂.4THFbut also some of the same compounds formed at the lower ratio are alsoproduced here. The VCl₂.ZnCl₂.4THF is a novel compound and can beseparated as a product of the process by crystallization as the productmix is cooled or concentrated. The structural formula was determined tobe: ##STR1## which can also be written (THF)₄ V(μ-Cl)₂ ZnCl₂. Thus Zn/Vratios in the catalyst can vary from zero to 1 in the final product,generally 0.1 to 1, more generally 0.5 to 1. The ratio of Zn to V usedto make the product can vary from 0.5:1 or less to 2:1 or more butgenerally will be in the 0.5:1 to 1:1 range. The structural formula andatom ratios shown here for the final product are composite or averagefigures and the exact compound shown may or may not exist in any greatquantity. This is true when using either Zn metal or Et₂ Zn. Cooling thereduction mixture evidently favors V⁺³ over V⁺². By using 1/3 mole of areducing agent such as triethylborane, VCl₄.2THF may be reduced at roomtemperature over several days time or at 80° C. for one hour to thered-orange VCl₃.3THF. Instead of the organoboron reducing agent, anorganoaluminum reducing agent as defined above may be used. The productsof reactions using a zinc component as the sole reducing agent consistof a mixture of three compounds with the formulae VCl₃.ZnCl₂.5THF,VCl₂.ZnCl₂.4THF and VCl₃.3THF which are light green, aqua and red-orangein color, respectively. The relative proportion of these productsdepends upon the amount of reducing agent such as zinc and the reactionconditions chosen. For instance, higher zinc levels, Zn/V atom ratio=1favor the VCl₂ compound while lower zinc levels, Zn/V atom ratio=0.5favor the VCl₃ products. Cooling the mixture seems to stop the reductionat VCl₃ ; as in the zinc reduction of VCl₃.3THF, reduction to V+2 occursslowly at temperatures below 60° C. as determined by visual observationof the color change. Thus when the starting material is VCl₄, preferablyat least a part of the reaction is carried out at a temperature of atleast 60° C., preferably 65° to 130° C., most preferably 65° C. to 100°C.

The VCl₂ ZnCl₂.4THF can be dissolved in a chlorinated hydrocarbonsolvent and on standing VCl₂ ZnCl₂.2THF precipitates, this material alsobeing a novel compound. This precipitation can be speeded up by gentleheating. For instance, if dichloromethane is the solvent, heating at100° C. under pressure to maintain liquid conditions gives a 78 percentyield in 15 minutes. Other suitable solvents are halogenatedhydrocarbons, particularly chlorinated and dichlorinated hydrocarbonssuch as ethyl chloride, and 1,2-dichloroethane. Also suitable is CCl₂FCCl₂ F or CCl₂ FCClF₂. Generally heating at 50° to 100° C. will beused.

The catalyst is preferably formed and thereafter combined with thesupport, although it is possible to first combine the support with theingredients and thereafter carry out the complexing and/or reducingreactions. Reduction after combination with the support would preferablybe carried out using a hydrocarbon soluble reducing agent such as adialkyl zinc compound, i.e. a solid reducing agent which is not solublecould not be used.

ln some instances, it may be desirable to carry out the reduction andthe formation of the ether complex essentially simultaneously. This isaccomplished by simply combining the reducing agent as defined above inether with VCl₃ or VCl₄. The formation of the vanadium complex from VCl₃and ether may be accelerated by the presence of a catalytic agent suchas sodium hydride, the same as in the first route. Alternatively, thestarting material can be VCl₄ and the presence of an adequate(stoichiometric) amount of reducing agent such as triethylborane tobring the vanadium to the +3 oxidation state alone or with the principalreducing-agent to give VCl₃ and ultimately VCl₂. In this case, R₂ Zn isnot suitable as the principal reducing agent because of the followingreactions

VCl₄ +BR₃ →VCl₃ +BCl₃

BCl₃ +R₂ Zn→RBCl₂ +RZnCl. The second reaction which is not desirabledoes not occur with zinc metal.

The simultaneous complex formation and reduction reaction is carried outat a temperature of 20° to 130° C. with 70° to 100° C. preferred and atatmospheric to moderate pressure to maintain the ether as a liquid. Thereagents must be added slowly or incrementally with adequate time forstepwise reduction to occur. Reduction with triethylborane at roomtemperature takes several days, while at 90° C. the reaction is completein one hour.

The support can be any porous support conventionally utilized incatalytic reactions. However, the presence of a support is absolutelyessential since the unsupported material, while active as a catalyst, isof no practical utility because it causes reactor fouling. Suitablesupports include catalytic grade silica such as Davison 952 MS, aluminasuch as Ketjen Grade B, magnesium oxide, aluminum phosphate orphosphated alumina. Aluminum phosphate having a phosphorus to aluminumratio of about 0.6:1 to 0.9:1 and phosphated alumina prepared bytreating alumina with a phosphating agent such as orthophosphoric acidcan also be used. Generally, the phosphorus to aluminum ratio on thesurface will be within the range of 0.1:1 to 1:1, preferably 0.2:1 to0.9:1. Suitable phosphorus-containing bases are disclosed in detail inMcDaniel et al U.S. Pat. No. 4,364,841 (Dec. 21, 1982), the disclosureof which is hereby incorporated by reference.

The support is generally calcined or otherwise treated generally in anoxygen-containing ambient such as air at an elevated temperature to dryand/or activate same as is well known in the art before being treatedwith catalyst. Generally activation temperatures of 150°-800° C.,preferably 400°-600° C. are utilized with the aluminum phosphate bases.Silica, alumina and phosphated alumina bases generally are activated ata temperature of 450°-1000° C. Subsequent to the activation, the baseand the catalyst are combined. By porous base is meant a substratehaving a surface area within-the range of 100 to 600, preferably 300 to500 square meters per gram.

The vanadium complex catalyst is incorporated in the support preferablyin an amount where the support is saturated. With alumina this is about3 weight percent vanadium based on the weight of the support withactivity falling off at 1 percent or less. Broadly 0.1 to 10, preferably0.5 to 3 weight percent is used.

The vanadium complex catalyst component and the support can be combinedin any suitable manner which assures dispersal of the catalyst componenton the surface of the support. Generally this will be done by forming aslurry of the catalyst component and the support in a solvent for thecatalyst component, and separating the thus impregnated supportedcatalyst from excess solution. Preferred solvents are polar non-proticnormally liquid materials such as dichloromethane or chloroform,preferably dichloromethane. This can be done by filtering and thenwashing with the solvent and optionally thereafter with a hydrocarbonsuch as pentane, hexane, heptane or any normally liquid volatilealiphatic hydrocarbon. The slurry can be formed by first dissolving thevanadium complex and slurrying with the silica or by mixing the solidsand then adding solvent. Any inert liquid, which will dissolve thevanadium complex can be used with methylene chloride being particularlysuitable. Remaining solvent after the wash step can be removed undergentle conditions and in an inert atmosphere such as vacuum or a flowingnitrogen or argon stream. Room temperature up to 50° C. is suitable.Optionally, it can be left as a slurry in the hydrocarbon wash liquid.

The catalysts of this invention can be used to polymerize at least onemono-1-olefin containing 2 to 8 carbon atoms per molecule. The catalystswill also catalyze other reactions as is well known with vanadiumcatalysts but one of the advantages of this invention is that thecatalysts are effective in producing olefin polymer without undesirableside reactions. The catalysts are of particular applicability inproducing ethylene homopolymers and copolymers of ethylene and one ormore comonomers selected from 1-olefins containing 3 to 8 carbon atomsper molecule such as propylene, 1-butene, 1-pentene, 1-hexene and1-octene. If it is the object to produce a copolymer, 0.5 to 20 molepercent comonomer or more can be used, enough to give 0.4 to 3 weightpercent incorporation of comonomer being preferred.

These polymers can be produced by solution polymerization or slurrypolymerization using conventional equipment and contacting processes.Contacting of the monomer or monomers with the catalyst can be effectedin any manner known in the art of solid catalysts. One convenient methodis to suspend the catalyst in an organic medium and to agitate themixture to maintain the catalyst in suspension throughout thepolymerization process.

The catalyst of this invention is particularly suitable for these slurrypolymerization systems and is capable of giving a complete spectrum ofpolymer so far as melt flow is concerned, including ultra high molecularweight polymer, utilizing a single catalyst.

While hydrogen is known as a molecular weight control agent, thecatalysts of this invention display an extraordinary sensitivity tohydrogen so that by controlling the amount of hydrogen utilizedeverything from ultra high molecular weight polymer through polymers ofmolding or even injection molding grade can be produced.

When hydrogen is used in the prior art, it is generally used at partialpressures up to 120 psia (0.8 MPa), preferably within the range of 20 to100 psia (0.14 to 0.69 MPa). These same amounts of hydrogen can also beused in this invention, although because of the high sensitivity tohydrogen, it may be preferred in the present invention to use 5 to 20psia when relatively high molecular weight polymer is desired.

When hydrogen is utilized it does tend to reduce activity and in suchinstances, it is desirable to use an adjuvant (activator). Suitableadjuvants include dibromomethane, bromochloromethane, dichloromethane,1,1,3-trichlorotrifluoromethane, 1,2-dichlorotetrafluoroethane anddichlorodifluoromethane. A particularly suitable material is1,2-difluorotetrachloroethane. Of course these adjuvants can be used inthe absence of hydrogen but their use is not necessary generally becauseof the extraordinarily high activity of the catalyst. The activator isgenerally used in an amount within the range of 1 to 5000 ppm based onthe solvent in the polymerization zone, different ranges apply todifferent activators. With CFCl₂ CFCl₂, 20 to 500 ppm is preferred.

With slurry polymerization of ethylene and predominantly ethylenecopolymer systems, the preferred temperature range is generally about200°-230° F. (93°-110° C.) although 66°-110° C. can be used. Thecatalysts of this invention do not have any undesirable induction timebetween the initial contact with the monomer and the initiation ofpolymerization.

Suitable polymerization solvents or diluents include straight chain andcyclic hydrocarbons such as normal pentane, normal hexane, cyclohexaneand other conventional polymerization solvents.

The catalysts of this invention are used in conjunction with acocatalyst. The cocatalyst is an organometal compound includingorganoboron compounds. Suitable compounds include (1) organoaluminumcompounds of the formula R_(m) AlX_(3-m) where R is a hydrocarbon groupof 1 to 12 carbon atoms, X is hydrogen or a halogen atom or an alkoxygroup, and m is 1-3 inclusive, (2) organoboron compounds of the formulaR₃ B where R is as defined above, and (3) organomagnesium compounds ofthe formula R₂ Mg where R is as defined above, with 2 to 6 carbon atomdialkyl magnesium compounds being preferred. The preferred cocatalystsare alkylaluminum compounds of the above formula wherein R is a 2 to 4carbon atom alkyl radical, most preferably triethylaluminum.

The cocatalyst is utilized in an amount so as to give an atom ratio ofmetal or boron to vanadium within the range of 1000:1 to 1:1, preferably200:1 to 10:1. Based on the solvent in the polymerization zone, theamount of metal compound cocatalyst is generally within the range of1000 to 1, preferably 500 to 10 parts by weight per million parts byweight of the solvent or diluent, these amounts being based on the totalreactor contents when no solvent or diluent is used. The cocatalyst canbe premixed with the catalyst or added as a separate stream or both.

EXAMPLE 1--CATALYST PREPARATION (UNSUPPORTED) A. Comparison Catalysts

1. VCl₃.3THF (THF is tetrahydroduran).

A mixture of zinc dust, 1.58 g (24.1 mmoles) and VCl₄.2THF, 16.26 g(48.2 mmoles) was placed in a glass pressure bottle in a glove box andwhile cooling in an ice bath, 50 mL (425 mmoles) of THF was addedresulting in a vigorous reaction and formation of a red slurry. Thereaction mixture was warmed to about 25° C. and then heated for one hourat 80° C. After cooling overnight, the mixture was filtered yielding redand green solids weighing 18.7 g. The crude product was slurried in 150mL of THF, heated to reflux and filtered. The filtrate was concentratedslightly resulting in the formation of red crystals which were collectedand weighed 2.76 g. Analysis indicated the product to be VCl₃.3THF. Atomratio: V⁺⁴ /Zn°=2.

2. VCl₃.ZnCl₂.5THF.

A three-neck flask fitted with a condenser was charged with 16.5 g (49.0mmoles) of VCl₄.2THF and THF to form a suspension. The mixture washeated to reflux and 3.20 g (49.0 mmoles) of zinc dust was slowly addedresulting in a vigorous reaction. The reaction mixture refluxed for onehour and filtered hot. A light blue solid was collected, which analysissubsequently showed to be VCl₂.ZnCl₂.4THF (also in supported forminvention catalyst 2) and a light green solid slowly crystallized in thefiltrate. The green solid was collected, washed with THF and dried undervacuum and found to weigh 5.81 g. Analysis subsequently indicated thegreen product to be VCl₃.ZnCl₂.5THF. Atom ratio: V⁺⁴ /Zn°=1. B.Invention Catalysts.

1. 2VCl₂.ZnCl₂.6THF.

A glass pressure bottle placed in a glove box (dry box) was charged with10.0 g (26.8 mmoles) of VCl₃.3THF, 0.88 g (13.4 mmoles) of zinc dust and40 mL (340 mmoles) of THF. The bottle was then placed in an oil bath at90° C. for 30 minutes and then cooled yielding a forest (grass) greencrystalline solid. The solid was recovered and dried under a vacuum.Analysis indicated the product to be 2VCl₂ ZnCl₂.6 THF. Atom ratio: V⁺³/Zn°=2. Thus this compound is produced by contacting VCl₃.3THF in THFwith about one-half mole of zinc or an alkyl zinc compound.

2. VCl₂.ZnCl₂.4THF.

Described earlier under comparison catalyst 2.

3. VCl₂.ZnCl₂.4THF.

A glass pressure bottle was charged with 18.14 g (53.8 mmoles) ofVCl₄.2THF, 3.52 g (53.8 mmoles) of zinc dust and 50 mL (425 mmoles) ofTHF was added. A vigorous reaction occurred following which the bottleand reaction mixture were heated for one hour at 70° C. A tan-coloredsolid was filtered off in a glove box and washed with THF leaving a palegreen solid. A portion of the solid, 15.95 g, was extracted in a soxhletwith 200 mL of THF. An aqua-colored, crystalline solid weighing 4.1 gwas isolated from the extract. Analysis indicated the product to beVCl₂.ZnCl₂.4THF. Atom ratio: V⁺⁴ /Zn°=1.

Any or all of the previous catalysts can be supported individually on asupport as described earlier in the specification. For example, 1 g ofKetjen Grade B alumina, previously calcined at 600° C., was added to aschlenk tube under argon with 0.40 g of invention catalyst 1,2VCl₂.ZnCl₂.6THF. The tube was shaken to mix the contents, 20 mL ofmethylene chloride was added and the mixture was stirred briefly. Thetube was transferred to a glove box and the colorless supernatant liquidremoved by filtration. The product was washed several times with 20 mLportions of fresh methylene chloride and then dried by gentle heating ina nitrogen stream to yield a pale green catalyst. Since the impregnatedcatalyst retained the color of the divalent vanadium compound employed,it is believed that impregnation, per se, does not alter the valencestate of the vanadium.

EXAMPLE 2--ETHYLENE POLYMERIZATION WITH UNSUPPORTED CATALYSTS

Ethylene was polymerized in a 1 gallon (3.8L) stirred, stainless steelreactor at 100° C. for 1 hour using 2L of isobutane as diluent, 2.0mmoles of 1,2-difluorotetrachloroethane (CFCl₂ CFCl₂), when employed asan exemplary halocarbon activator, 1.0 mmole of triethylaluminums (TEA)dissolved in n-heptane as cocatalyst, unless specified otherwise, and 80psi (0.55 MPa) of hydrogen, when employed. In each run, the diluent,cocatalyst, CFCl₂ CFCl₂, if employed, catalyst and hydrogen, ifemployed, were charged to the dry, clean reactor at about 20° C. Thetemperature was then raised to 100° C. and sufficient ethylene wascharged to obtain a differential Pressure of 230 Psi (1.6 HPa) and therun was started. The total reactor pressure in the runs ranged fromabout 505 to 555 psia (3.5 to 3.8 MPa) as shown and it was maintained atthe desired pressure by additional ethylene from a pressurized reservoiras needed.

In the various runs, the atom ratio of aluminum in the TEA to thevanadium contained in the catalyst ranged from a low of about 17:1, to ahigh of about 102:1, but mostly from about 17:1 to about 70:1 The weightof TEA per 1,000,000 parts isobutane diluent ranged from about 50 ppmTEA in Run 1 to about 100 ppm TEA in Runs 2-14. The differences in theamounts of TEA employed over the above ranges are deemed to be notcritical in evaluating the polymerization results.

Each polyethylene recovered from the reactor was dried, weighed toascertain the yield and the melt index determined in accordance withASTM D 1238-65, Condition E (MI) and Condition F (HLMI).

The results are set forth in Table I.

                                      TABLE I                                     __________________________________________________________________________    Unsupported Catalysts                                                                Run                                                                              Catalyst      Productivity                                                                          H.sub.2.sup.(a)                                                                  Employed                                   Comparison                                                                           No.                                                                              Compound  Wt. g                                                                             g PE/g cat/hr                                                                         psi                                                                              CFCl.sub.2 CFCl.sub.2                                                                MI HLMI                             __________________________________________________________________________    "      1  VCl.sub.3.3THF                                                                          0.0411                                                                             1,000   0 No     0.sup.(b                                                                          0                               "      2  VCl.sub.3.3THF                                                                          0.0142                                                                             3,310   0 Yes    0   0                               "      3  VCl.sub.3.3THF                                                                          0.0209                                                                            23,800  80 Yes    1.3                                                                               51                              "      4  VCl.sub.3.ZnCl.sub.2.5THF                                                               0.0064                                                                             2,660   0 Yes    0   0                               "      5  VCl.sub.3.ZnCl.sub.2.5THF                                                               0.0138                                                                             4,640  80 Yes    1.6                                                                               61                              "      6  2VCl.sub.2.ZnCl.sub.2.6THF                                                              0.0155                                                                            23,700   0 Yes    0   0                               "      7  2VCl.sub.2.ZnCl.sub.2.6THF                                                              0.0214                                                                            31,100  80 Yes    0   0                               "      8  2VCl.sub.2.ZnCl.sub.2.6THF                                                              0.0036                                                                            34,800  80 Yes    2.1                                                                               95                              "      9  VCl.sub.2.ZnCl.sub.2.4THF                                                               0.0317                                                                              725   80 No     2.2                                                                              131                              "      10 VCl.sub.2.ZnCl.sub.2.4THF                                                               0.0281                                                                            24,000  80 Yes    1.0                                                                              119                              "      11 VCl.sub.2.ZnCl.sub.2.4THF                                                               0.0080                                                                            15,300  80 Yes    6.8                                                                              190                              "      12 VCl.sub.2.ZnCl.sub.2.2THF                                                               0.0179                                                                              400   80 No     5.5                                                                              192                              "      13 VCl.sub.2.ZnCl.sub.2.2THF                                                               0.0097                                                                            31,300  80 Yes    1.1                                                                               52                              __________________________________________________________________________     .sup.(a) Hydrogen was measured as the pressure drop from a 0.325 L vessel     .sup.(b This run used 0.5 mmole of TEA.                                  

All of the catalysts employed in Table I caused reactor fouling when runwith or without CFCl₂ CFCl₂ as an activator and/or with or withouthydrogen to regulate molecular weight of the polymer. In Run 3, usingcomparison catalyst 1 (VCl₃.3THF) and in Runs 6, 7, 8, 10, 11 and 13using the invention catalysts, good productivities are obtained when theactivator is present. The catalysts containing divalent vanadium appearto be slightly more active than the trivalent vanadium contained in thecomparison catalysts.

EXAMPLE 3--ETHYLENE POLYMERIZATION WITH VANADIUM COMPOUNDS SUPPORTED ONALUMINA

Ketjen Grade B alumina, a commercial material having a pore volume ofabout 1.7 cc/g and a surface area of about 320 m² /g, was employed asthe support in this example. Before contacting with the vanadiumcompound, in a typical activation process, 50 g of the support werefluidized with air in a quartz tube at 600° C. for 3 hours. Aftercooling to 400° C., the air stream was supplanted with dry nitrogen andthe sample was allowed to cool to about 25° C. It was then stored undernitrogen in a sealed flask.

The supported catalysts in a typical preparation were prepared bycontacting 1.0 g of the calcined alumina and 10 mL of methylene chloridein a schlenk tube under argon and to it was added about 0.3 g of thevanadium compound and the mixture was mixed well by shaking. Theimpregnated catalyst was recovered in a glove box by filtration andwashed several times with 20 mL of fresh methylene chloride.

ln preparing the supported catalysts, sufficient vanadium-containingmixture was used to insure that the support was saturated. The finalproduct was dried by gentle heating under a nitrogen stream. Plasmaemission analysis of the catalysts showed them to contain from about 2to 3 weight percent vanadium. The impregnated catalysts retained thecolors of the vanadium compounds used in preparing them.

Ethylene was polymerized in one hour runs at 100° C. with the supportedcatalysts in the reactor described in Example 2. In each instance, 2L ofisobutane was used as diluent, 1.0 mmole of TEA was employed ascocatalyst, 2.0 mmoles of CFCl₂ CFCl₂ as activator, 80 psi hydrogen, ifemployed, and an ethylene differential pressure of 230 psi.

The total reactor pressure in the runs varied from 515 to 535 psia (3.6to 3.7 MPa). divalent vanadium, a similar trend is observed in comparingthe productivity figure of Run 5, 40,500 g PE/g catalyst/hour, with thatof Run 7, 8,740 g PE/g catalyst/hour, or with Run 8, 10,200 g PE/gcatalyst/hour. The Run 5 catalyst contains a calculated Zn content ofabout 8.8 weight percent with an atom ratio of V/Zn of 2 whereas the Run7 or 8 catalyst contains a calculated Zn content of about 12 weightpercent with an atom ratio of V/Zn of 1.

A fairer comparison of the effect of the oxidation state of vanadium oncatalyst activity can be obtained by comparing catalysts containing thesame V/Zn atom ratio. For example, the trivalent vanadium catalyst usedin Run 3 has a calculated V/Zn atom ratio of 1 and produced 2,520 g PE/gcatalyst/hour and the divalent vanadium catalysts of Runs 7 or 8 havingcalculated V/Zn atom ratios of 1, produced 8,740 and 10,200 g PE/gcatalyst/ hour, respectively, under identical reaction conditions. Also,in comparing the trivalent vanadium catalyst of Runs 1, 2 (no zinc),with the divalent vanadium catalyst of invention Runs 5 and 6 (V/Zn atomratio of 2), it is apparent that the divalent catalyst is more active.

EXAMPLE 4--ETHYLENE POLYMERIZATION WITH VANADIUM COMPOUNDS SUPPORTED ONVARIOUS SUBSTRATES

The supports used in this Example were selected from commerciallyobtained materials from the group Ketjen Grade B alumina (disclosed inExample 3), Davison high pore volume alumina having a surface area of540 m² /g and a pore volume of 2.0 cc/g, and Davison 952 silica having asurface area of 300 m² /g and a pore volume of 1.6 cc/g and anexperimental AlPO₄, P/Al atom ratio of 0.9, having a surface area of 350m² /g and a pore volume of 0.8 cc/g. The phosphated alumina, P/Al₂ O₃,was prepared by treating a previously calcined (600° C.) sample of theDavison alumina with a methanolic solution of H₃ PO₄ at theconcentration needed to provide the P/Al atom ratio of 0.1 desired. Theexcess methanol was removed by suction filtration and the support driedunder vacuum at 80° C. for 12 hours.

The catalysts consisting of either 2VCl₂.ZnCl₂.6THF or VCl₃.3THF and thespecified support were made by impregnation as previously described.

Ethylene polymerization was carried out in a 2L stirred, stainless steelreactor containing 1.25 lbs. (about 567 g or 1L) of isobutane asdiluent. Charge order, method of maintaining reactor pressure, which inthese runs was about 565 psia (3.9 Mpa), and polymer recovery wasfollowed as described before. The weights of catalysts charged,polymerization temperature employed, hydrogen and halocarbon activatorused, if any, and polymer results obtained are set forth in Tables IIIA,and IIIB. One mmole of cocatalyst was used in each run, generally TEA,except where diethylaluminum chloride is specified.

                                      TABLE IIIA                                  __________________________________________________________________________    Run Parameters And Results For Supported Vanadium Catalysts                   Catalyst                                 Viscosity                            Run                                                                              V       Cat. Wt.                                                                           Productivity                                                                          H.sub.2                                                                          (CFCl.sub.2).sub.2                                                                     Density                                                                            Intrinsic                                                                          Melt                            No.                                                                              Cpd.                                                                             Support                                                                            g    g PE/g cat/hr                                                                         psi                                                                              mmole                                                                              HLMI                                                                              g/cc g/dl M poise                         __________________________________________________________________________      1.sup.(a)                                                                      A  AlPO.sub.4.sup.(b)                                                                 0.0428                                                                             3,620   20 2.0   16.sup.(h)                                                                       0.9636                                                                             2.44 --                              2  A  Al.sub.2 O.sub.3.sup.(c)                                                           0.0357                                                                             4,340   20 2.0   38.sup.(i)                                                                       0.9651                                                                             1.78 --                              3  A  SiO.sub.2.sup.(d)                                                                  0.0270                                                                             2,040   20 2.0  113.sup.(j)                                                                       0.9687                                                                             .sup.  --.sup.(g)                                                                  --                              4  A  Al.sub.2 O.sub.3.sup.(e)                                                           0.0727                                                                             1,620   0  0    0   0.9273                                                                             --   90                              5  A  Al.sub.2 O.sub.3.sup.(c)                                                           0.0930                                                                             1,540   0  0    0   0.9294                                                                             --   95                              6  A  Al.sub.2 O.sub.3.sup.(c)                                                           0.0681                                                                             2,470   0  0    0   0.9282                                                                             --   130                             .sup. 7.sup.(f)                                                                  B  Al.sub.2 O.sub.3.sup.(c)                                                           0.0374                                                                             4,810   0  0    0   0.9297                                                                             --   92                              .sup. 8.sup.(f)                                                                  B  AlPO.sub.4.sup.(b)                                                                 0.0458                                                                             3,100   0  0    0   0.9285                                                                             --   80                              __________________________________________________________________________     A is 2VCl.sub.2.ZnCl.sub.2.6THF.                                              B is VCl.sub.3.3THF (control).                                                .sup.(a) 1 mmole TEA cocatalyst in all runs except 7 and 8.                   .sup.(b) P/Al atom ratio of 0.9, calcined at 600° C. in air for 3      hours.                                                                        .sup.(c) Ketjen Grade B alumina calcined at 600° C. in air for 3       hours.                                                                        .sup.(d) Davison 952 silica calcined at 700° C. in air for 3 hours     .sup.(e) Davison high pore volume alumina calcined at 600° C. in       air for 3 hours.                                                              .sup.(f) Used 1 mmole diethylaluminum chloride as cocatalyst.                 .sup.(g) Dash signifies no determination made.                                .sup.(h) MI = 0.23.                                                           .sup.(i) MI = 0.52.                                                           .sup.(j) MI = 2.0.                                                       

The heterogeneity index (Mw/Mn) as determined from gel permeationchromatography) for the Run 1 polymer is 11, Run 2 is 8.7 and Run 3 is17. These results show moderately broad to broad molecular weightdistribution polymer is made.

The nature of the support also plays an important role in catalystselection since catalyst productivity and sensitivity to the presence ofhydrogen and halocarbon activator are affected by the nature of thesupport. For example, in considering catalyst productivity and polymerHLMI for Runs 1 to 3 using AlPO₄, Al₂ O₃ and SiO₂ as supports, theresults show using the same divalent vanadium compound, that order ofcatalyst activity is Al₂ O₃, >AIPO₄ >SiO₂. On the other hand,sensitivity to hydrogen gives the ranking in decreasing order of SiO₂,Al₂ O₃ and AlPO₄ as supports.

In the absence of hydrogen, the polymers made are high molecular weightin nature having zero HLMI values based on Runs 4-6. Generally, absenceof a halocarbon activator also significantly diminishes catalystactivity.

Without an activator, there is no clear preference for the invention,catalysts using the vanadium dichloride complex versus the controlcatalysts using the vanadium trichloride complex, and in some instancesthe trichloride can even give higher productivity as a comparison ofRuns 6 and 7 shows. However, the invention catalysts are far moresensitive to the presence of an activator and the invention catalystsare more sensitive to the presence of hydrogen.

                                      TABLE IIIB                                  __________________________________________________________________________    Run Parameters And Results For Vanadium-Phosphated Alumina Catalysts          Catalyst (TEA Cocatalyst  Polymer Properties                                  Unless Otherwise Noted)            Viscosity                                  Run                                                                              V  Catalyst                                                                           Productivity                                                                          H.sub.2                                                                         (CFCl.sub.2).sub.2                                                                     Density                                                                            Intrinsic                                                                          Melt                                  No.                                                                              Cpd.                                                                             Wt. g                                                                              g PE/g Cat/hr                                                                         psi                                                                             mmole                                                                              HLMI                                                                              g/cc g/dl M poise                               __________________________________________________________________________     9 A  0.0978                                                                             3,350    0                                                                              0    0   0.9285                                                                             --   119                                   10 A  0.0237                                                                              28,000.sup.(a)                                                                        0                                                                              1.0  0   --   --   --                                    11 A  0.0156                                                                              31,500.sup.(b)                                                                        0                                                                              0.1  0   0.9284                                                                             --   134                                   12 A  0.0357                                                                             6,330   50                                                                              1.0  high.sup.(e)                                                                      0.9693                                                                             --   --                                    13 A  0.0340                                                                             3,240   50                                                                              1.0  high.sup.(f)                                                                      0.9688                                                                             --   --                                    14 A  0.0625                                                                             .sup.  3,580.sup.(c)                                                                  20                                                                              1.0  high.sup.(g)                                                                      0.9710                                                                             --   --                                    15 A  0.0634                                                                               7,260.sup.(d)                                                                        1                                                                              1.0  0   0.9395                                                                             --     34.5                                16 A  0.0294                                                                             6,730   10                                                                              1.0  4.8.sup.(h)                                                                       --   --   --                                    17 A  0.1040                                                                             1,970   80                                                                              2.0  51.sup.(i)                                                                        0.9662                                                                             --   --                                    18 A  0.0201                                                                             34,200   0                                                                              2.0  0   0.9253                                                                             28.6 --                                    19 B  0.1141                                                                             3,820   80                                                                              2.0  .sup.  0.6.sup.(j)                                                                0.9555                                                                             --   --                                    20 B  0.0347                                                                             17,200   0                                                                              2.0  0   0.9271                                                                             29.4 --                                    __________________________________________________________________________     A is 2VCl.sub.2.ZnCl.sub.2.6THF.                                              B is VCl.sub.3.3THF.                                                          .sup.(a) 14,000 productivity for 30 minutes, for 60 minutes assuming          linear response calculated productivity equals 14,000 × 60 ÷ 30     = 28,000.                                                                     .sup.(b) 16,800 productivity for 32 minutes, see note .sup.(a) for            correcting to 60 minutes.                                                     .sup.(c) 3,700 productivity for 62 minutes, see note .sup.(a).                .sup.(d) 4,730 productivity for 39.1 minutes, see note .sup.(a).              .sup.(e) MI is 140.                                                           .sup.(f) MI is 209.                                                           .sup.(g) MI is 15.1.                                                          .sup.(h) MI is 0.08.                                                          .sup.(i) MI is 1.2.                                                           .sup.(j) MI is 0.                                                        

The atom ratio of Al (or B)/V employed in the runs set forth in TablesIIIA and IIIB ranged from about 14 to 123, assuming each supportedcatalyst contains 2 weight percent vanadium. For 3 weight percentvanadium, the corresponding atom ratios range from about 17 to 102.

The results in Tables IIIA and IIIB taken together show that the natureof the support has a marked effect on the hydrogen sensitivity of thedivalent vanadium catalysts employing the support. For example,comparing the 0.52 melt index of the Run 2, Table IIIA polymer with themelt index of 15 obtained with the polymer of Run 14 of Table IIIB inwhich a phosphated alumina, P/Al atom ratio of 0.1, is employed inpreparing the catalyst, clearly shows the advantage for thevanadium/phosphated alumina combination.

In the absence of reactor hydrogen and halocarbon activator, phosphatedalumina, vanadium halide catalysts show reasonably good activity, e.g.,3,350 g PE/g catalyst/hour, and ultrahigh molecular weight polyethylene(UHMWPE) having densities about 0.928 g/cc as shown in Run 9, isproduced.

In the absence of reactor hydrogen but addition of from 0.1 to 2 mmolesof a halocarbon activator such as CFCl₂ CFCl₂, Runs 10, 11 and 18demonstrate that catalyst activity is substantially increased, e.g.,about 8 to 10 fold based on Run 9, while UHMWPE is produced havingdensities of about 0.9Z8 g/cc.

In the presence of 1.0 mmole CFCl₂ CFCl₂ and hydrogen varying from 1 to50 psi, Runs 12-16 demonstrate that a spectrum of polyethylenes can beprepared ranging from UHMWPE at 1 psi hydrogen in Run 15 to lowmolecular weight polymer having a melt index of 209 in Run 13. Run 15also shows that a small amount of hydrogen in the reactor along with 1.0mmole halocarbon significantly increases the polymer density, e.g., fromabout 0.9Z8 g/cc in absence of hydrogen and halocarbon (Run 9) to about0.940 g/cc, yet UHMWPE is the product.

In comparing invention Run 17 with control Run 19 of Table IIIB, bothrun in the presence of 80 psi hydrogen and 2.0 mmoles activator, it isapparent that the invention catalyst is much more sensitive to hydrogensince the polymer made has a HLMI of 51 vs. 0.6 for Run 19 polymer.Under the conditions employed, however, the invention divalent vanadiumcatalyst has about one-half the activity of the control trivalentvanadium catalyst based on productivities.

In the absence of reactor hydrogen but in the presence of 2.0 mmoleactivator, the invention divalent vanadium catalyst in Run 18 has abouttwice the activity of the control trivalent vanadium catalyst used inRun 20. Both catalysts produced UHMWPE of approximately similarmolecular weights. However, the polymer made with the invention catalysthas a slightly lower density, 0.925 g/cc vs. 0.927 g/cc.

Melt viscosity data are obtained by means of a Rheometrics DynamicSpectrometer (RDS) at 230° C. using parallel plate geometry. Strainamplitude is 5%, nitrogen gas is used in the sample chamber and theoscillatory frequency is varied from 0.1 to 500 radian/second. The dataobtained give storage modulus and loss modulus as a function ofoscillatory frequency. From these data in turn can be calculated dynamiccomplex viscosity /η*/ as described in Chapter 1 of the "ViscoelasticProperties of Polymers", by Ferry, published in 1961 by Wiley. Thevalues obtained are directly related to polymer molecular weight. Thehigher the value the higher the molecular weight. It has been shown fora commercially available UHMWPE that /η*/ when determined at 0.1radian/second and 190° C. has a value of about 30 MPoise. Higher valuesthen indicate even higher molecular weight polymer. The values obtainedin Runs 4-8 of Table IIIA and Runs 9, 11 and 15 of Table IIIB areindicative that UHMWPE has been prepared. The polymer of Run 15, TableIIIB has about the same value as that of a commercially obtained UHMWPE(identified as Hostalen GUR, American Hoechst).

Intrinsic viscosities are determined in accordance with ASTM D 4021-81,modified by using 0.015 weight percent dissolved polymer rather than0.05 weight percent. The change is made to obtain better dissolution ofthe UHMWPE samples, which can be difficult to dissolve. Currently,UHMWPE is defined as one having an intrinsic viscosity of about 20 orhigher. The polymers of Runs 18 and 20 of Table IIIB give intrinsicviscosities of 28.6 and 29.4, respectively.

ln summary, the polymers made in invention Runs 4-6 of Table IIIA andinvention runs 9-11, 5 and 18 of Table IIIB can all be characterized asUHMWPE.

EXAMPLE V

In this series of experiments, vanadium tetrachloride was reacted withvarious ethers, thereafter reacted with TEB and finally contacted withzinc metal.

In the first run, the ether was the cyclic ether tetrahydropyran. Inthis run the zinc dust was reacted at 90° C. for one-half hour, andyielded a light green product, indicating that a complex had been formedbetween the ether and the vanadium which was susceptible of beingreduced by reaction with the zinc.

In the second run, xhe ether utilized was 1,2-dimethoxyethane. Evenafter heating for 7 hours at 90° C. no reaction was visible between thezinc dust and the other reactants.

In the third run, the ether was diethyl ether. Again, no reaction wasapparent on adding the zinc dust even after 3 hours at 90° C.

ln the final run, the ether was a di-n-butyl ether. Again, no reactionwas apparent on adding the zinc dust and no reaction was evident after 3hours at 90° C.

The above results indicate that cyclic ethers are effective incomplexing higher valent vanadium compounds such as vanadiumtetrachloride for subsequent reduction with a zinc component such aszinc metal to give vanadium dichloride but that noncyclic ethers are noteffective in this route, even though noncyclic ethers can be utilized inthe first route where the reduction to VCl₂ is achieved first.

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope thereof.

We claim:
 1. A polymerization process comprising:contacting at least onemono-1-olefin having 2-8 carbon atoms with a catalyst compositionconsisting essentially of a vanadium dihalide-ether complex on a solidporous carrier in the presence of an organometal compound wherein saidvanadium dihalide-ether complex is chosen from the group consisting ofVCl₂.ZnCl₂.2THF, VCl₂.ZnCl₂.4THF and 2VCl₂.ZnCl₂.6THF.
 2. A methodaccording to claim 1 wherein said olefin is selected from ethylene,propylene, 1-butene, and 1-hexene.
 3. A method according to claim 1wherein said olefin comprises ethylene.
 4. A method according to claim 1wherein said polymerization process is carried out at a temperaturewithin the range of 66°-110° C.
 5. A method according to claim 4 whereinsaid organometal present during said polymerization is an organoaluminumcompound.
 6. A method according to claim 5 wherein said organoaluminumcompound is triethylaluminum.
 7. A method according to claim 1 wherein ahalogenated hydrocarbon activator is present during said polymerization.8. A method according to claim 3 wherein (CFCl₂)₂ is present as anactivator during said polymerization, wherein said organometal istriethylaluminum, said vanadium dihalide is selected fromVCl₂.ZnCl₂.4THF and 2VCl₂.ZnCl₂.6THF, said porous carrier is selectedfrom at least one of silica, aluminum phosphate, phosphated alumina andalumina, said vanadium dihalide-ether complex being used in an amount togive 0.1 to 10 wt. % vanadium based on the weight of said porouscarrier, and wherein said polymerization is carried out under slurryconditions at a temperature within the range of 93° to 110° C.
 9. Amethod according to claim 1 wherein hydrogen is used as a molecularweight control agent.
 10. A method according to claim 2 wherein saidporous carrier is selected from at least one of silica, aluminumphosphate, phosphated alumina, and alumina.
 11. A method according toclaim 12 wherein said carrier is selected from at least one of silica,aluminum phosphate, phosphated alumina, and alumina.
 12. A methodaccording to claim 1 wherein said VCl₂.ZnCl₂.4THF complex is formed by amethod comprising contacting THF with VCl₄ in a chlorinated hydrocarbonsolvent to give a VCl₄ -THF complex andthereafter contacting said VCl₄-THF complex with a reducing agent selected from at least one of zincmetal and organozinc compounds to give a product comprisingVCl₂.ZnCl₂.4THF.
 13. A process of claim 1 wherein said complex is chosenfrom VCl₂.ZnCl₂.4THF and 2VCl₂.ZnCl₂.6THF.
 14. A polymerization processcomprising:contacting at least one mono-1-olefin having 2 to 8 carbonatoms with a catalyst composition consisting essentially of a vanadiumdihalide-ether complex on a solid porous carrier in the presence of avanadium dihalide-ether complex on a solid porous carrier in thepresence of an organometal compound wherein said vanadium dihalide-ethercomplex on a solid porous carrier is produced by contacting a cyclicether with a vanadium compound selected from VX₄ and VX₃ where X is ahalogen to form a first complex; contacting sad first complex with areducing agent at least part of which is selected from zinc metals andorganozinc compounds to reduce the valence of said vanadium to +2 and;combining the thus produced VX₂ -ether-zinc complex with said poroussupport.
 15. A method according to claim 14 wherein said complex is2VCl₂.ZnCl₂.6THF.
 16. A method according to claim 14 wherein saidvanadium compound is VCl₄ and said VCl₄ is reacted in a chlorinatedhydrocarbon solvent with said ether, said ether being THF, to give VCl₄-THF complex; thereafter contacting said VCl₄ -THF complex with saidreducing agent to give a product comprising VCl₂.ZnCl₂.4THF.
 17. Amethod according to claim 14 wherein said complex is VCl₂.ZnCl₂.2THF.